Method for obtaining combination starters for Bulgarian yoghurt

Abstract

Specific strains of the micro-organisms Lactobacillus bulgaricum and Streptococcus thermophilus are isolated, identified and purified and used for the preparation of starting materials for production of Bulgarian sour milk. The use of these micro-organisms is described together with procedures in the present invention for the production of Bulgarian sour milk having improved nutrient value and improved characteristic taste and flavor. Specified mixtures of the above micro-organisms can also be advantageously employed for this purpose.

What is claimed is: 
     
       1. Method for obtaining combination starters for the production of Bulgarian sour milk which comprises the following steps: (a) innoculating each of a plurality of portions of sterile cow milk with a combination starter containing microorganism strains selected from the group consisting of Lactobacillus bulgaricus Numbers 5, 26, 37 and 144 and another microorganism strain selected from the group consisting of Streptococcus thermophilus Numbers 12, 14, 18 and 22 to form a plurality of inoculums;   (b) cultivating the plurality of inoculums at 44° to 46° C. to cause coagulation and observing the coagulation times;   (c) subsequent to said coagulating, selecting from the plurality of coagulated inoculums, combination starters that cause said coagulation in about two hours and have desired cellular configuration and desired ratio between said Lactobacillus and Streptococcus strains;   (d) subsequent to said selecting, inoculating with about 1% of said selected combination starters a plurality of portions of sterile sheep milk or a mixture of sheep and cow milk in a ratio of 1:1 to form a plurality of inoculums containing said selected combination starters,   (e) subsequent to step (d), carrying out subculturing of said plurality of inoculums by daily inoculation in said sheep milk or said mixture of each said selected combination starter innoculated in (d) during the first four months and weekly for two additional months;   (f) selecting from the combination starters subcultured in step (e) the combination starters that maintain consistant desired cellular configuration and consistant desired ratio between said Lactobacillus and Streptococcus strains throughout said subculturing; and   (g) testing the combination starters selected in step (f) for producing Bulgarian sour milk having desired properties.   
     
     
       2. Method in compliance with claim 1 in which the ratio of the two strains in step (f) is 1:3 to 1:10. 
     
     
       3. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 5 and Streptococcus thermophilus Number 12. 
     
     
       4. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 5 and Streptococcus thermophilus Number 22. 
     
     
       5. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 37 and Streptococcus thermophilus Number 18. 
     
     
       6. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 37 and Streptococcus thermophilus Number 12. 
     
     
       7. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 144 and Streptococcus thermophilus Number 12. 
     
     
       8. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 144 and Streptococcus thermophilus Number 14. 
     
     
       9. Method according to claim 1 wherein the combination starter contains Lactobacillus bulgaricus Number 26 and Streptococcus thermophilus Number 12. 
     
     
       10. A method of making sour milk using a combination starter produced by the method of claim 1.